Low voltage “QC” pendants manufactured by W.A.C. Lighting of Garden City, N.Y. utilize a coaxial suspension cable both for support and power. The cable has an inner, central power conductor surrounded by an outer, braided earth conductor. As described in U.S. Pat. No. 6,884,095, the disclosure of which is incorporated herein by reference, a male coax connector for the cable comprises a central post assembly having first, top and second, lower coaxial, cylindrical contact portions 94 and 95, respectively, electrically isolated from each other by a cylindrical insulating member 96. An internally threaded, metal, attachment collar 97 receives the lower cylindrical contact portion 95 and connections to the coax core wire and braid are established during assembly by tightening respective upper and lower set screws 98 and 99 threaded in the upper contact portion 94 and in the attachment collar 97.
However, if, during assembly, the lower set screw that establishes electrical contact with the braid is over-tightened, it can penetrate the insulation of the core conductor, between the core conductor and the braided earth, where the insulation passes through the collar into the upper, contact tip portion 94 so that the lower set screw then contacts the core, with the result that, when plugged in, current will not flow to the lamp but short through the braid, tripping a circuit breaker and/or possibly damaging a transformer. To avoid risk of such short circuit, an electrical continuity tester is employed to check that the braid and tip contact portion 95 remain electrically isolated in a ‘power off’ condition.
Most prior continuity testers have two (metal) probes connecting an internally battery to a status lamp, and the probes are pressed against the normally electrically isolated locations, such as the first and second set screws or the upper contact portion portion 94 and the collar or braid with the pendant light lamp removed to break the circuit, so that, normally, the tester status lamp will only glow when a short exists.
The need to electrically engage two separate points simultaneously by touch is a relatively fiddlesome procedure and requires a self test prior to each operational test to ensure that tester circuitry is operational, (charged battery etc).